Dosing valve for a fluid product dispenser

ABSTRACT

A metering valve for a fluid dispenser, the metering valve having a valve body that defines a metering chamber in which a valve member slides between a rest position and an actuated position, the valve body and/or the valve member being made by injection-molding a material having a PBT matrix and glass microspheres dispersed in said PBT matrix.

The present invention relates to a metering valve for a fluid dispenser.

The preferred field of application of such a valve is the field of pharmacy, but this type of valve may also be used in other fields, e.g. the fields of cosmetics or perfumery.

The metering valves of the prior art comprise a valve body that defines a metering chamber in which a valve member slides between a rest position and an actuated position. The valve body and the valve member are usually made by molding plastics materials of the polymer type, such as polyethylene (PE), polypropylene (PP), polyacetal or polyoxymethylene (POM), or polybutylene terephthalate (PBT). However, metering valves must satisfy requirements for small manufacturing tolerances, and they must provide great dimensional stability for the very small components making them up. There is also a requirement for the metering-valve components to be accurately cylindrical, which is necessary for maintaining the points of sealing in the valve, despite a pressure of 5 bars that exists in the reservoir. There are also requirements for the materials used in the components that constitute the metering valves to have excellent mechanical properties, in particular given the high level of stresses to which they may be subjected, in particular while filling the reservoir through said metering valve and/or while the metering valve is being used by the patient. Other constraints can also affect the reliability of metering valves, such as operating with significant pressure differentials, or abrasion associated with the presence of powder.

Injection molding is very widely used for producing parts intended for applications in the packaging, electricity, automotive, cosmetics, and consumer goods industries. The method is also used in high-tech industries such as the medical, pharmaceutical, aeronautical, and nuclear industries.

The appearance of the injected parts is a very important criterion, in particular for medical applications for which a high level of quality is essential in order to guarantee the safety of patients. Thus, certain defects in appearance may be generated while manufacturing the parts, and monitoring such defects in large scale production can turn out to be tricky. Unfortunately, the presence of defects, in particular on safety parts, may generate malfunctions or fragility of devices such as metering valves. Various types of defect exist, in particular burrs, webs, air bubbles, streaks, or even incomplete parts.

Such defects can be remedied in several ways, e.g. by modifying the parameters of the injection-molding method, by modifying the design of the part to be molded, or by adding additives to the polymers so as to improve their molding performance.

Nuclei forming agents are the additives most often used, in particular for eliminating surface defects. Nuclei forming agents act by modifying the crystallization kinetics. Nuclei forming agents may be talc-based or they may be organic substances. Other substances, such as foaming agents may also be used. They decompose during the molding process so as to give a foam structure. They may be based on sodium bicarbonate and sodium citrate.

Documents FR 3 035 382, WO 2012/072962, FR 2 767 801, and DE 27 34 950 describe prior-art devices.

An object of the present invention is to provide a pump that does not have the above-mentioned difficulties.

Another object of the present invention is to provide such a metering valve that makes it possible to dispense fluid in reliable, regular, and reproducible manner each time the dispenser is actuated.

Another object of the present invention is to provide a metering valve that is simple and inexpensive to manufacture and to assemble.

The present invention thus provides a metering valve for a fluid dispenser, the metering valve comprising a valve body that defines a metering chamber in which a valve member slides between a rest position and an actuated position, said valve body and/or said valve member being made by injection-molding a material comprising a PBT matrix and glass microspheres dispersed in said PBT matrix.

Advantageously, said glass microspheres have a diameter lying in the range 1 micrometer (μm) to 2000 μm, advantageously in the range 1 μm to 100 μm.

Advantageously, said glass microspheres are added to the PBT matrix at a content lying in the range 1% to 20% by weight, advantageously in the range 1% to 15% by weight.

The present invention also provides a fluid dispenser comprising a reservoir containing fluid to be dispensed, and a metering valve as described above.

Advantageously, said dispenser contains a hydrofluoroalkane (HFA) gas as a propellant gas.

These characteristics and advantages and others appear more clearly from the following detailed description, given by way of non-limiting example, and with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic section view of a metering valve in an advantageous embodiment;

FIG. 2 is a bar chart comparing the Young's modulus of PBT on its own and with various additives, with the Young's modulus of PBT including microspheres of the invention; and

FIG. 3 is a graph comparing the coefficient of friction of PBT on its own with the coefficient of friction of PBT including microspheres of the invention.

In the following description, the terms “upper”, “lower”, “top” and “bottom” refer to the upright position shown in FIG. 1, and the terms “axial” and “radial” refer to the longitudinal axis of the valve shown in FIG. 1.

The metering valve shown in FIG. 1 is of the retention type. However, it should be understood that this is merely an example, and that the present invention applies to any type of metering valve.

The valve includes a valve body 10 that extends along a longitudinal axis A. Inside said valve body 10, a valve member 30 slides between a rest position, that is the position shown in FIG. 1, and a dispensing position in which the valve member 30 has been pushed into the valve body 10.

The valve is for assembling on a reservoir 1, preferably by means of a fastener element 5 that may be a crimpable, screw-fastenable, or snap-fastenable capsule, and a neck gasket 6 is advantageously interposed between the fastener element and the reservoir. Optionally, a ring 4 may be assembled around the valve body, in particular so as to decrease the dead volume in the upsidedown position, and so as to limit contact between the fluid and the neck gasket. The ring may be of any shape, and the example in FIG. 1 is not limiting.

The valve member 30 is urged towards its rest position by a spring 8 that is arranged in the valve body 10 and that co-operates firstly with the valve body 10 and secondly with the valve member 30, preferably with a radial collar 320 of the valve member 30. A metering chamber 20 is defined inside the valve body 10, said valve member 30 sliding inside said metering chamber so as to enable its contents to be dispensed when the valve is actuated.

In conventional manner, the metering chamber is preferably defined between two annular gaskets, namely a valve-member gasket 21, and a chamber gasket 22.

FIG. 1 shows the valve in the upright storage position, i.e. the position in which the metering chamber 20 is arranged above the reservoir 1.

The valve member 30 includes an outlet orifice 301 that is connected to an inlet orifice 302 that is arranged in the metering chamber 20 when the valve member 30 is in its dispensing position. The valve member 30 may be made of two portions, namely an upper portion 31 (also known as a valve-member top) and a lower portion 32 (also known as a valve-member bottom). In this embodiment, the lower portion 32 is assembled inside the upper portion 31. An internal channel 33 is provided in the valve member 30 that makes it possible to connect the metering chamber 20 to the reservoir 1, so as to fill said metering chamber 20 after each actuation of the valve when the valve member 30 returns to its rest position under the effect of the spring 8. Filling is performed when the device is still in its upsidedown working position, with the valve arranged below the reservoir.

In the invention, said valve body and/or said valve member is/are made by injection-molding a material comprising a PBT matrix and glass microspheres dispersed in said PBT matrix.

Although molding PBT is problematic with crystallinity varying greatly from one batch to another, the addition of glass microspheres in a PBT matrix makes it possible to control crystallinity of the material and thus reduce molding problems.

The solid glass microspheres are made of glass, advantageously recycled glass, and present the advantage of containing neither free silica nor heavy metals. They are in powder form. They have a basic pH, which is favorable when it is desired to limit interaction with the active ingredients. They may be subjected to a surface treatment with a coupling agent, which is selected as a function of the nature of the matrix, and which enables better adhesion between the microsphere and the matrix, and also better dispersion.

The glass microspheres typically have a diameter lying in the range 1 μm to 2000 μm. In the various tests performed and described below, glass microspheres were used of diameter lying in the range 3 μm to 100 μm, with a median diameter lying in the range 10 μm to 30 μm. The microspheres may be added to the PBT matrix at a content lying in the range 1% to 20% by weight, advantageously in the range 1% to 15% by weight.

Adding glass microspheres into a PBT matrix makes it possible, in particular, to obtain the following improvements:

-   -   during molding, the microspheres make it possible to reduce the         variability of crystallinity between the various batches of         materials, and thus to reduce difficulties during molding; in         particular this makes it possible to reduce substantially or to         eliminate difficulties of the components deforming, and to         improve their dimensional stability;     -   the microspheres make it possible to increase the mechanical         properties of the material in which they are dispersed; in order         to characterize the mechanical strength of a material, traction         measurements are performed, thereby making it possible to obtain         breaking stress values or Young's modulus values; FIG. 2 shows a         significant improvement in the Young's modulus for PBT with the         glass microspheres compared to PBT on its own, and also compared         to PBT with various well known additives, such as a nuclei         forming agent, talc, or a foaming agent;     -   the glass microspheres are of inorganic origin, thus they do not         add any additional extractables; on the contrary they have a         diluting effect; thus, with a content of glass microspheres of         13% in a PBT matrix, a reduction in extractables of a little         more than 15% has been observed.     -   the microspheres make it possible to reduce the coefficient of         friction; the coefficient of friction is the ratio of the         traction force (response force enabling the apparatus to move)         over the applied force (normal force); two types of coefficient         of friction exist: the dynamic coefficient and the static         coefficient; the static coefficient is the coefficient measured         at the beginning of a test; it is the force necessary to move         the sample on the substrate and to initiate movement; the term         “coefficient of adhesion” is also used; the dynamic coefficient         is the coefficient necessary for movement to be maintained at a         constant speed; in this embodiment, values for the dynamic         coefficient are used since the system is thus stable and at         constant speed; the test consisted in causing a steel ball to         rub against a defined material (specifically PBT, with and         without microspheres) so as to determine a coefficient of         friction; the results obtained are reproduced in FIG. 3 and they         show that adding microspheres makes it possible to reduce the         coefficient of friction; in particular, this makes it possible         to envisage a reduction in difficulties with friction in valves;     -   microspheres do not have any impact on compatibility with active         ingredients; this has been tested by putting PBT containing         microspheres into direct contact with active ingredients (e.g.         formoterol fumarate), and by measuring the degradation of the         active ingredients using analytical techniques; the tests         performed did not show the glass microspheres having any impact         on such degradation.

The present invention is described above with reference to an advantageous embodiment, but naturally any modification could be applied thereto by the person skilled in the art, without going beyond the ambit of the present invention, as defined by the accompanying claims. 

1. A metering valve for a fluid dispenser, the metering valve comprising a valve body that defines a metering chamber in which a valve member slides between a rest position and an actuated position, the metering valve being characterized in that said valve body and/or said valve member is/are made by injection-molding a material comprising a PBT matrix and glass microspheres dispersed in said PBT matrix.
 2. A valve according to claim 1, wherein said glass microspheres have a diameter lying in the range 1 μm to 2000 μm, advantageously in the range 1 μm to 100 μm.
 3. A valve according to claim 1, wherein said glass microspheres are added to the PBT matrix at a content lying in the range 1% to 20% by weight, advantageously in the range 1% to 15% by weight.
 4. A fluid dispenser comprising a reservoir (1) containing fluid to be dispensed, said dispenser being characterized in that it further comprises a metering valve according to claim
 1. 5. A dispenser according to claim 5, containing an HFA gas as a propellant gas. 